Sound amplifying device



June 9, 1931. Q E, oss

SOUND AMPLIFYING DEVICE Filed May 21, 1928 Carmen E. Ross.

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Aff'orne Patented June 9, 1931 UNITED STATES PATENT OFFICE CARMEN E.ROSS, OF VANCOUVER, BRITISH COLUMBIA, CANADA, ASSIGNOR TO W. WYLLIEJOHNSTON, TRUSTEE, OF VANCOUVER, CANADA SOUND AMPLIFYING DEVICE Aplication filed May 21, 1928, Serial No. 279,476, and in Canada March28, 1928.

This invention relates to sound amplifying devices, such as are used inconnection with radio apparatus as loud speakers, or with phonographsand the like, for increasing and concentrating the sound whilstretaining the original clarity and distinctiveness of the tone values.

The primary object of the invention is to provide a device of thischaracter which will transmit and amplify sonorous vibrations over awide range of scale without confusion or impairment of their tonalcharacteristics.

I effect this by utilizing a tube having a gradually increasing crosssectional area proportioned in reference to its length and the size ofits apertures on well known acoustic principles. This I curve (over aportion of its length) into a convenient volute form in a plane which issubstantially right-angular to the axis of its bell-mounted outlet, theen tire tube or tubular cavity as the case may be being embedded in orencased by some suitable solid medium.

By this construction the direction of the impulse of the sound waves inone portion of the device is right-angular to the same in another partand possibly secondary vibrational effects which might be set upwithinthe body of the enclosing material are neutralized, thus effecting ormaintaining the clarity of tone obtained by my device.

A preferred embodiment of my device is shown in the drawings herewithforming a part of this application, in which:

Fig. 1 is a vertical section through the centre line of the bell-mouthedaperture shown in Fig. 3. V

Fig. 2 is an end view of Fig. 1.

Fig. 3 is a plan.

Fig. 4 is a section on line A-A of Fig. 1 looking in the direction ofthe right hand arrow points.

Fig. 5 is a section on line BB of Fig. 1.

Fig. 6 is a section on line A-A of Fig. 1 looking in the direction ofthe left hand arrow points.

In these drawings it will be observed that the device is by preference,formed in and by a solid wood block, say of pine or spruce, which forconvenience is divided into three sections 7 8, 9 to facilitate thecarving of the internal tubular passage.

These sections 7 8, 9 are dowelled together and finally glued so as toeffect substantially a solid block. The intake aperture 10 is adapted toreceive or be connected to the usual microphone unit or other deviceproviding the initial sonorous vibrations from a pulsatingr diaphragm.

he tube 11 leading from the aperture 10 is continued to form theconvolution terminatin at 12 where its direction makes a curvingright-angular change as shown at 13 through sections 8 towards section 7where it turns upwardly at 14 and thence by a third rounded bend throughanother rightangular turn into the trumpet-shaped portion 15 to theflared exit aperture at 16.

In operation the sound. impulses enter at 10 pass around the volute 11changing their direction by three right-angular turns into thetrumpet-shaped exit at 16. These curved but otherwise abrupt turns inthe tubular path produce a resonance efiect which adds to the amplifyingqualities of the tube, their external vibrational efi'ects beingabsorbed by the surrounding wood block and any directional effect beingneutralized by the right-angular flow of their transmission.

Having now particularly described my in- Vention, what I claim as newand desire to be protected in by Letters Patent, is:

A sound amplifying device comprising a series of three corresponding andadjacent rectangular blocks, one surface of the middle block in saidseries and the adjacent surface of the outer block of said series beingchanneled in convolutionary form whereby a tubular cavity of circularcross section is formed by the combination of the two blocks, theextremities of said tubular cavity being connected with surfaceapertures in the said blocks and in planes which are right-angular toeach other, central and correspondingly connected apertures transverselyof said. convolutionary cavity in both said blocks, the other surface ofthe said middle block and that of the other outer block adjacent theretobeing similarly channeled to connect the said central aperture and oneof the said extremities, whereby a continuous tapered tubular cavity isproduced Within the said three blocks, the said oavity'being so formedthat a convolution around a straight portion is obtained.

In testimony whereof I aflix my signature.

CARMEN E. BOSS.

